Tilting Wheeled Vehicle

ABSTRACT

A tilting, preferably three-wheeled, vehicle is disclosed that has a tilting mechanism that allows the vehicle to have leaning characteristics substantially similar to those offered by an in-line two-wheeled vehicle, but that does not require complex linkages and/or control systems to operate effectively. A tilting linkage is operably secured to a frame to allow a pair of spaced apart wheels to remain substantially aligned with the plane of the vehicle throughout its range of movement while still allowing the steering axes of each wheel to intersect the substantially vertical centerline of each wheel. The linkage also allows the caster angle of each wheel&#39;s pivot axis can be optimized independently of the angle of the vehicle&#39;s handlebar steering shaft.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.11/507,040, which issued as U.S. Pat. No. 7,487,985 on Feb. 10, 2009,and it claims priority to U.S. provisional patent application Ser. No.60/711,922, filed on Aug. 25, 2005.

FIELD OF THE INVENTION

This invention relates to wheeled vehicles such as motorcycles and thelike. More particularly, this invention relates to a stable, preferablethree-wheeled vehicle that offers maneuverability characteristics thatare substantially similar to those of an in-line, two-wheeled vehicle.

BACKGROUND OF THE INVENTION

Unlike a typical three and four wheeled vehicles, in-line, two-wheeledvehicles, such as motorcycles, bicycles, and the like, allow a rider tolean or tilt while turning without urging the rider toward the outsideof the turn. Instead, the rider of the in-line two-wheeled vehicle ispushed straight down into the seat as the free leaning motorcyclebalances the vertical gravity vector with the horizontal vector createdby going around a corner. The faster the rider goes around a corner, themore the in-line two-wheeled vehicle needs to lean.

But two-wheeled in-line vehicles are limited by only having one fronttire as well as having the rider sitting high on the vehicle. The onefront tire limits the amount of braking and amount of traction that canbe achieved.

Efforts to apply tilting characteristics to three and four-wheeledvehicles have had limited success. Examples of such vehicles and theirlimitations are discussed in greater detail in an article titled “SomeTechnical Aspects of Tilting Trikes,” by Tony Foale, B. Tech, M.Eng.Sc.dated Mar. 21, 1999, the disclosure of which is hereby incorporated byreference.

In general, these known tilting three-wheeled vehicles are limited bynot allowing proper tilt of the vehicle, complex tilting structures thatrequire excessive user interaction, and/or requiring complex controlsystems to operate effectively.

SUMMARY OF THE INVENTION

Despite the available three-wheeled vehicles, there remains a need for athree-wheeled vehicle that allows leaning substantially similar to thatoffered by an in-line two-wheeled vehicle, but that does not requirecomplex linkages and/or control systems to operate effectively. Inaddition to other benefits that will become apparent in the followingdisclosure, the present invention fulfills these needs.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a rear, right, isometric view of a tilting three-wheeledvehicle in accordance with an embodiment of the present invention.

FIG. 2A is a front, plan view of the tilting three-wheeled vehicle ofFIG. 1 showing a possible straight position of the vehicle and the frontwheels aligned to urge the vehicle in a straight direction.

FIG. 2B is a front, plan view of the tilting three-wheeled vehicle ofFIG. 1 showing a possible leaning position of the vehicle with the frontwheels aligned to urge the vehicle in a straight direction.

FIG. 3 is a front, plan view of the tilting three-wheeled vehicle ofFIG. 1 showing a possible leaning position of the vehicle and the frontwheels turned to define a possible right turn.

FIG. 4 is a partial, enlarged, isometric view of the right wheelassembly of the tilting three-wheeled vehicle of FIG. 1.

FIG. 5 is a front, isometric view of an alternative linkage for use on atilting three-wheeled vehicle in accordance with an embodiment of thepresent invention.

FIG. 6 is a left, isometric view of the alternative linkage of FIG. 5showing a possible orientation on a motorcycle chassis shown in brokenlines.

DETAILED DESCRIPTION OF THE INVENTION

A tilting three-wheeled vehicle 10 with an improved pivoting pair ofspaced-apart steering wheels 12 a, 12 b operably secured thereto with atilting linkage 14 extending between the steering wheels 12 a, 12 b andthe vehicle 10 is disclosed in FIGS. 1-6. A first preferred tiltinglinkage 14 is shown in FIGS. 1-4, and a second preferred tilting linkage14′ is shown in FIGS. 5 & 6.

Referring to FIGS. 1-4, the vehicle 10 replaces the front wheel of atwo-wheeled in-line vehicle with the pair of substantiallyparallelly-aligned wheels 12 a, 12 b joined to the vehicle 10 by alinkage 14 that tilts each wheel 12 a, 12 b substantially similar to thetilt of the vehicle 10 during use.

In one disclosed embodiment best shown in FIGS. 2A, the linkage 14 hasan upper and lower spaced-apart and substantially elongate cross members20, 22, respectively, that are each pivotally secured to the front ofthe vehicle at respective pivots 24, 26. The upper and lower spacedapart cross-members 20, 22, are substantially parallelly aligned, withthe pivots 24, 26 for each cross-member being substantially aligned onthe steering axis 30 of the vehicle 10.

Auxiliary steering shafts 32, 34, which are also referred to as“kingpins” herein, are operably secured to the distal ends of eachrespective cross member defining a left steering shaft 32 extendingbetween the left distal ends 40 of the upper and lower cross-members 20,22 and a right steering shaft 34 extending between the right distal ends42 of the upper and lower cross-members 20, 22. The left and rightsteering shafts 32, 34 are substantially parallelly aligned with eachother and the steering axis 30 of the vehicle and have substantially thesame caster angle 50 (FIG. 4).

In one embodiment, the king pins preferably do not go through the centerof their respective wheel axis but rather are set back toward the rearof the vehicle approximately 2.5 inches to allow the contact patch ofthe tire to be slightly behind an imaginary line that goes down thecenter of the king pin. Alternatively, no offset need be provided solong as each wheel's caster angle 50 (FIG. 4) is adjusted accordingly.

Each wheel 12 a, 12 b of the pair of wheels 12 is operably secured toone of the steering shafts 32, 34. The left wheel 12 b is operablysecured to the left steering shaft 32 and the right wheel 12 a isoperably secured to the right steering shaft 34 so as to allow eachwheel 12 a, 12 b to turn about its respective steering axis B, C.Accordingly, the steering axes B & C of the left and right wheel 12 a,12 b are substantially parallelly aligned with the steering axis 30 ofthe vehicle 20 and each wheel 12 a, 12 b is able to turn about itsrespective steering shaft 32, 34. More preferably, each steering shaft32, 34 is aligned so that its respective steering axis B, C iscoincident with a substantially vertical plane 200, 202 intersecting thelongitudinal center 204, 206 of the respective wheel as best shown inFIG. 2A.

Preferably, the handlebars 60 of the vehicle 10 operably engage aprimary steering shaft 62 (FIG. 3), which defines the steering axis 30of the vehicle. A first tie rod 64 extends from a lower portion of thesteering shaft 62 to the right wheel 12 a, and a second tie rod 66extends from the right wheel 12 a to the left wheel 12 b as shown.Accordingly, when a rider turns the handlebars 60, the steering shaft 62rotates in the commanded direction thereby urging the first tie rod 64to turn the right wheel 12 a about the right steering shaft 34. Thesecond tie rod 66 simultaneously urges the left wheel 12 b to pivot inthe same commanded direction about the left steering shaft 32.Accordingly, it can be appreciated that the vehicle may be steered insubstantially the same manner as a conventional in-line two-wheeledvehicle.

Preferably and referring to FIGS. 2A & 4, a suspension system 70, suchas a spring 72 and/or dampener 71, operably engage each wheel 12 a, 12 bas shown.

More preferably, the steering system components are configured so as toprovide conventional Ackermann steering.

The present invention allows a three-wheeled vehicle to leansubstantially similarly to an in-line two-wheeled vehicle. Referring toFIGS. 2A, 2B and 3, when the steering axis 30 of the vehicle is alignedsubstantially vertically as shown in FIG. 2A, both the left wheel 12 band right wheel 12 a are aligned substantially vertically. However,during turning operations, such as a right turn shown in FIG. 3, whenthe vehicle naturally leans into the turn, the left and right wheelsalso lean by substantially the same amount. Referring to FIG. 2B, a leanto the right will also cause the left and right wheels to lean right bysubstantially the same amount.

Referring to FIGS. 5 & 6, an alternative preferred tilting linkage 14′is disclosed. In order to reduce undue repetition, like elements betweenthis embodiment and the previously disclosed tilting linkage 14 are likenumbered.

The alternative preferred linkage 14′ of FIGS. 5 & 6 preferably has apair of upper cross members 20 a, 20 b and a vertically spaced apartpair of lower cross members 22 a, 22 b respectively. Each cross member20 a, 20 b, 22 a, 22 c is pivotally secured to the front of the vehicleat respective, substantially horizontal, pivot shafts 24′, 26′. Namely,cross members 20 a, 20 b are pivotally secured to pivot shaft 24′ andlower cross members 22 a, 22 b are pivotally secured to pivot shaft 26′.The pivot shafts 24′, 26′ are positioned substantially vertically withrespect to each other along the steering axis 30 and spaced apart fromeach other as best shown in FIG. 5. Accordingly, the distal ends ofupper cross member 20 a and lower cross member 22 a move substantiallyin the directions of arrow 100 and the distal ends of upper cross member20 b and lower cross member 22 b move substantially in the directions ofarrows 102 as the steering shaft tilts about arrow 104.

Auxiliary steering shafts 32, 34, which are also referred to as“kingpins” herein, are operably secured to the distal ends of eachrespective cross member defining a left steering shaft 32 extendingbetween the left distal ends 40 of the upper and lower cross-members 20b, 22 b and a right steering shaft 34 extending between the distal ends40 of the upper and lower cross-members 20 a, 22 a. The left and rightsteering shafts 32, 34 are substantially parallelly aligned with eachother.

If desired, the caster angle 50 (FIG. 4) of the left and right steeringshafts 32, 34 can differ from the caster angle of the steering axis 30.More preferably, the castor angle 50 of the left and right steeringshafts 32, 34 is selected so that there is about a 2.5 inch to 3.5 inchtrail, defined as the distant between the contact patch of therespective wheel 12 a, 12 b with the ground and the contact point withthe ground of an imaginary line extending from the respective steeringshaft 32, 34. More preferably, the trail for each wheel 12 a, 12 b isabout 3 inches. It can be appreciated that since the steering axis 30 isseparate from the kingpins, any steering axis angle may be used tooptimize driver handlebar positioning while still allowing for theoptimizing each wheel's caster angle.

Each wheel 12 a, 12 b of the pair of wheels 12 is operably secured toone of the steering shafts 32, 34. The left wheel 12 b is operablysecured to the left steering shaft 32 and the right wheel 12 a isoperably secured to the right steering shaft 34 so as to allow eachwheel 12 a, 12 b to turn about its respective steering axis B, C.Accordingly, the planes of the left and right wheel 12 a, 12 b aresubstantially parallely aligned with the steering axis 30 of the vehicle20 and each wheel 12 a, 12 b is able to turn about its respectivesteering shaft 32, 34.

Preferably, the handlebars 60 of the vehicle 10 operably engage aprimary steering shaft 62 (FIG. 5), which defines the steering axis 30of the vehicle. A first tie rod 64 a extends from a lower portion of thesteering shaft 62 to operably engage the right wheel 12 a, and a secondtie rod 64 b extends from the lower portion of the steering shaft 62 tooperably engage the left wheel 12 b as shown. Accordingly, when a riderturns the handlebars 60, the steering shaft 62 rotates in the commandeddirection thereby urging the first tie rods 64 a, 64 b to turn theirrespective wheels in the commanded direction. Accordingly, it can beappreciated that the vehicle may be steered in substantially the samemanner as a conventional in-line two-wheeled vehicle.

Preferably and referring to FIGS. 5 & 6, a suspension system 70′, suchas a spring 120 and/or dampener 122, operably engages the linkage 14′.More preferably, the spring 120 and dampener 123 are pivotally securedto both the left and right portions of the linkage 14′ at pivots 114,112, respectively as shown. Accordingly, both the left and rightportions of the linkage 14′ are independently movable in the directionsof arrows 102, 100, respectively, while also being urged to a neutral,substantially horizontal configuration with respect to each other.

More preferably, the tie bars 64, 66 are sized to as to allow the outerwheel in a given turn to turn slightly less in the commanded directionthan the inner wheel of the turn.

The disclosed embodiments allow positioning of a driver low in thevehicle 10 behind the engine. Preferably, placing the engine to the rearwould create a vehicle too light in the front where most of the brakingoccurs and would can make the vehicle prone to oversteering issues whichwould lead to spin outs. Placing the motor in the front would mostlikely lead to an understeering vehicle, which would be a safersituation when driving at the vehicle's limits. Lowering of thevehicle's center of gravity is universally seen as desirable and reducesthe chance of the vehicle flipping over which is very difficult to do ona motorcycle or like vehicle unless the wheels encounter some nonmovable object such as a curb or rock. This characteristic is know bymotorcyclists as “highsiding” and tends to sling the rider up over thetop of their bike. Lowering the vehicle's center of gravity will allowthe vehicle to shift from a left to right turn faster than a similarvehicle with a higher center of gravity.

This three-wheeled vehicle 10 of the present invention allows it tosteer and maneuver like a conventional in-line two-wheeled vehicle buthave better braking and traction capabilities. With the driver sittinglow in the vehicle like in a sports car he would not have theuncomfortable feeling of being tossed left or right when cornering hard.

There are two ways to achieve a leaning vehicle. One way is to have thevehicle “free lean” such as a motorcycle where the steering input is theonly force needed to create the lean. A free leaning vehicle needs to beable to lean at up to a 45-50 degree angle to allow for a maximum leanrequired during a fast tight turn. If the free leaning vehicle ismechanically challenged in that it cannot achieve such a lean withoutpart of the chassis hitting the pavement or some binding occurring inthe leaning mechanism, then the forces are not adequately balanced andthe driver begins to feel the force of being toss to the outside. Thisalso causes the force on the tires to no longer be straight down and cancause the vehicle to slide as motorcycles do not have much of a contactpatch on the pavement and are not designed to handle side load forces.

The other way to achieve a leaning vehicle relies on complex controlsystems such as computer input from steering sensors to commandhydraulic actuators as needed to force the vehicle to lean.

The present invention relies on a free leaning design. It has beendesigned to have no clearance issues up to 45 degrees so it should beable to lean up to all angles required by the driver regardless of speedor sharpness of turn. It will steer like a motorcycle and require use ofcountersteering to control. This method of steering is familiar to allmotorcyclists who are able to switch back and forth between steering acar and a motorcycle with no confusion. Anyone truly wanting to learn todrive a motorcycle is not put off by the fact that it steers differentlythan a car. In fact, many motorcyclists do not even realize that theyare using countersteering to control their bike and just do itintuitively. People who have not driven motorcycles before may find thevehicle difficult to control until they learn how to steer it properly.

The preferred embodiment of the present invention is also far lessexpensive and complicated to manufacture than any forced leaningvehicle.

With increased up front traction and braking capabilities of amotorcycle combined with a lower center of gravity than a motorcycleoffered by at least one embodiment of the present invention, the vehicleof the present invention will outperform motorcycles with the same sizeengine despite being slightly heavier due to the additional steeringlinkage and additional wheel.

Known tilting vehicles mislocate the kingpins which are offset towardthe center of the vehicle similar to how an automobile's steering isbuilt. By centering the kingpin left to right inside the wheel of amotorcycle type tire and rim and bringing the kingpin inclination angle(or known as Steering Inclination Angle (SIA) or Steering AxisInclination (SAI)) to 0 degrees, the present invention achieves asubstantially 0 scrub radius when the vehicle is tracking in a straightline which is substantially similar to how a motorcycle's steeringworks. The scrub radius will then shift from positive to negative as thevehicle leans with one side being positive and the other being negativeat the same lean angle.

The castor of the kingpins can also mimic that of a motorcycle and be inthe range of 24-30 degrees. Sport motorcycles have a smaller castorangle while “choppers” have a lot more. The first disclosed embodimenthas a middle of the range 27 degrees. The second disclosed embodimenthas a preferred castor angle of about 15 degrees. Of course, othercaster angles could be used depending on a particular application.

The camber is preferably set up to be slightly positive. Accordingly,the inside tire preferably leans slightly more since it is following asmaller radius. While traveling straight ahead, both tires will want topull slightly to the outside but their forces should offset each other.At slower speeds (i.e. 1-5 mph), the rider will turn the steering to theright in order to turn the vehicle right. At speeds higher than that,the effect of countersteering kicks in and the rider must turn thesteering to the left in order for the vehicle to go to the right.

Currently, unless supported by the driver's feet or by a kickstand, thevehicle 10 of the present invention remains free-leaning, like amotorcycle. Accordingly, it will tend to tilt sideways when operating atvery slow speeds, when stopped, and when parked. Accordingly, it canfall-over, just like a motorcycle, unless supported by the rider or akickstand.

If desired, the vehicle can be configured to reduce or eliminatefreeleaning when stopped or operated at slow speeds. For example, thefront of the vehicle can be temporarily and automatically locked at acommanded, straight position at slow speeds and when stopped with nopivoting allowed along pivots 24 and 26.

Such control systems for detecting speed and activating a controller tolimit movement are known. For example, the speed control could beactivated by a connection to a traditional speedometer measuring therotation of the wheel since the vehicle would lock up anytime the brakeswere applied hard enough to lock up the wheels. Alternatively, vehiclespeed can be monitored by an on-board GPS system, a radar system, aradio frequency transmission system or the like that would measure thevehicle's true speed and apply a mechanical lock once the speed of thevehicle reaches less than say 3 mph. With such a system installed, thedriver would not have to put his or her feet on the ground once thevehicle came to a stop.

Moreover, the tilting linkage 14 and 14′ can include a frame portion 130adapted to fit onto the front end of a conventional in-line two-wheeledvehicle such as a conventional motor cycle or the like. Such frame wouldinclude conventional fittings and the like to allow the steering shaft30 to detachably connect to the existing handlebar system of theconventional in-line two-wheeled vehicle.

In view of the wide variety of embodiments to which the principles ofthe invention can be applied, it should be apparent that the detailedembodiments are illustrative only and should not be taken as limitingthe scope of the invention. For example, although the disclosedembodiment positions the pair of wheels 12 a, 12 b on the front of thevehicle, the principles of this invention would also work with the pairof wheels 12 a, 12 b replacing the rear wheel of an in-line two-wheeledvehicle. Similarly, a four-wheeled vehicle with one or both of the pairsof wheels configured as described could also operate effectively.Rather, the claimed invention includes all such modifications as maycome within the scope of the claims and equivalents thereto.

1. A tilting three wheeled vehicle having: an elongate frame defining aframe plane extending substantially vertically along a longitudinalcenterline of said frame, said frame tiltable from side-to-side defininga range of movement of said frame; a tilting linkage operably secured tothe frame, said tilting linkage operably securing a first wheel and asecond wheel spaced apart from and aligned substantially parallel tosaid first wheel; said first wheel pivotally secured to said linkagedefining a first pivot axis and having a substantially verticallongitudinal centerline defining a first wheel plane that intersectssaid substantially vertical longitudinal centerline, said first pivotaxis substantially intersecting said first wheel plane; said secondwheel pivotally secured to said linkage defining a second pivot axis andhaving a second substantially vertical longitudinal centerline defininga second wheel plane that intersects said second substantially verticallongitudinal centerline, said second pivot axis substantiallyintersecting said second wheel plane; and, said first steering axis andsaid second steering axis aligned substantially parallel to said frameplane through said range of movement of said frame.
 2. The tiltingwheeled vehicle of claim 1, wherein said frame has a front, a back, aleft side, and a right side and said frame is tiltable so that saidframe plane may tilt in the direction between said left side and saidright side, and further including: a rear wheel operably secured towardthe back of said frame; said tilting linkage is operably secured towardthe front of said frame thereby defining the tilting three-wheeledvehicle.
 3. The tilting wheeled vehicle of claim 2, wherein said tiltinglinkage includes: a substantially horizontal first pivot operablysecured to the frame substantially near said longitudinal centerline ofsaid frame; a substantially horizontal second pivot operably secured tothe frame substantially near said longitudinal centerline of said frame;said first and second pivots spaced apart from each other with saidfirst pivot positioned substantially vertically above said second pivot;an upper arm pivotally secured to said first pivot and having a firstdistal end; a lower arm pivotally secured to said second pivot andhaving a second distal end; a kingpin extending between said upper armand said lower arm toward said first and second distal ends, saidkingpin aligned substantially parallel to the frame plane of thevehicle; and, a wheel operably secured to said kingpin.
 4. The tiltingwheeled vehicle of claim 3, wherein said upper arm has an opposite thirddistal end and said lower arm as an opposite fourth distal end, andfurther including: a second kingpin extending between said upper arm andsaid lower arm toward said third and fourth distal ends, said secondkingpin aligned substantially parallel to the frame plane of the vehicleand said first kingpin; and, a second wheel operably secured to saidsecond kingpin.
 5. The tilting vehicle of claim 1, wherein said vehicleis a conventional motorcycles and said linkage is detachably secured tosaid motorcycle.
 6. The tilting vehicle of claim 2, further including asteering shaft operably secured to said frame, said steering shaftaligned substantially parallel to said frame plane.
 7. The tiltingvehicle of claim 6, further including a handle bar operably secured tosaid steering shaft, and a steering linkage extending between saidsteering rod and said first and second wheels so as to allow a rider toturn said first and second wheels about said first and second kingpins,respectively, by turning the handle bar about said steering shaftthereby steering the vehicle.
 8. The tilting vehicle of claim 1, furtherincluding a suspension system operably secured to said linkage.
 9. Thetilting vehicle of claim 8, wherein said suspension system includes acompression spring operably positioned between said first wheel and saidkingpin.
 10. The tilting vehicle of claim 1, wherein said tiltinglinkage includes: a substantially horizontal first pivot operablysecured to the frame substantially near said longitudinal centerline ofsaid frame; a substantially horizontal second pivot operably secured tothe frame substantially near said longitudinal centerline of said frame;said first and second pivots spaced apart from each other with saidfirst pivot positioned substantially vertically above said second pivot;a first upper arm pivotally secured to said first pivot and having afirst distal end; a first lower arm pivotally secured to said secondpivot and having a second distal end; a first kingpin extending betweensaid first upper arm and said first lower arm toward said first andsecond distal ends, said first kingpin aligned substantially parallel tothe frame plane of the vehicle; said first wheel operably secured tosaid first kingpin. a second upper arm pivotally secured to said firstpivot and having a third distal end; a second lower arm pivotallysecured to said second pivot and having a fourth distal end; a secondkingpin extending between said second upper arm and said second lowerarm toward said third and fourth distal ends, said second kingpinaligned substantially parallel to the frame plane of the vehicle; and,said second wheel operably secured to said first kingpin.
 11. Thevehicle of claim 10, further including a suspension system operablyconnected to said linkage.
 12. The vehicle of claim 11, wherein saidsuspension system is operably connected to said first upper and saidsecond upper arm.
 13. A linkage for use in a tilting three-wheeledvehicle having a handle bar rotatable about a steering shaft and asubstantially elongate frame defining a longitudinal plane along thecenterline of said vehicle, said linkage having: a substantiallyhorizontal first pivot operably secured to the frame substantially nearsaid longitudinal centerline; a substantially horizontal second pivotoperably secured to the frame substantially near said longitudinalcenterline; said first and second pivots spaced apart from each otherwith said first pivot positioned substantially vertically above saidsecond pivot; an upper arm pivotally secured to said first pivot andhaving a first distal end; a lower arm pivotally secured to said secondpivot and having a second distal end; a kingpin extending between saidupper arm and said lower arm toward said first and second distal ends,said kingpin defining a first wheel steering axis aligned substantiallyparallel to the longitudinal plane of the vehicle; a first wheeloperably secured to said kingpin and having a substantially verticallongitudinal centerline defining a first wheel plane; and, said firstwheel steering axis positioned substantially coincident with said firstwheel plane.
 14. The linkage of claim 13, wherein said upper arm has anopposite third distal end and said lower arm as an opposite fourthdistal end, and further including: a second kingpin extending betweensaid upper arm and said lower arm toward said third and fourth distalends, said second kingpin aligned substantially parallel to thelongitudinal plane of the vehicle and said first kingpin; and, a secondwheel operably secured to said second kingpin and having a substantiallyvertical longitudinal centerline defining a second wheel plane; and,said second wheel steering axis positioned substantially coincident withsaid second wheel plane.
 15. (canceled)
 16. The linkage of claim 14wherein said linkage is detachable secured to the front of aconventional motorcycle.
 17. The linkage of claim 16, further includinga suspension system operably secured to said linkage.
 18. The linkage ofclaim 14, wherein said second wheel has an interior hub and said secondking pin is operably positioned within said hub.